Visual Studio'NET 2005 Using RAD Tools for NTier Development

1
Visual Studio.NET 2005Using RAD Tools for N-Tier
Development

• Andy Beaulieu
• MCT, MCSD.NET

2
Drag/Drop Apps?

• Demo
• Using Server Explorer
• Drag/Drop Table onto Page
• Use Smart Tag for Formatting
• No code is generated instead, everything is
  declarative

3
Drag/Drop Apps?

• Looking at the source view

4
Pros and Cons

• Pros
• Very fast
• Little coding knowledge required
• Cons
• Easy to break (no validation)
• 2Tier Architecture
• No reusability
• Limited functionality (at some point, you have to
  code).

5
N-Tier Architecture

• With a bit more work, we can still use RAD tools
  but get an N-Tier Architecture.
• N-Tier provides reusability, scalability,
  maintainability.

6
N-Tier Architecture
7
Data Access Layer

• Provides Programmer Friendly components for
  retrieving and updating data
• Developer is freed from writing mundane and
  error-prone ADO.NET code
• Instead can concentrate on Business Logic

8
Data Access Layer

• TableAdapter is a new class ideal for creating
  DAL components
• Exists within context of a Typed DataSet
• Contains DB Connection logic, Select, Insert,
  Update, Delete commands.

9
Data Access Layer

• DEMO Using VS.NET 2005 Designers to create a DAL
  component (Typed DataSet TableAdapter)

10
Data Access Layer

• Note on WindowsForms Clients
• WindowsForms clients can take advantage of
  DataSet events for validation!
• Provides strongly typed row argument
• Not usable from ASP.NET client using
  ObjectDataSource

11
Business Logic Layer

• provides validation and workflow
• We will extend the Data Access Layer to provide
  BLL layer
• New ObjectDataSource component allows data
  binding between UI and BLL components

12
Business Logic Layer

• If we want to use ObjectDataSource component for
  data binding, we must follow some rules

13
Business Logic LayerRules for ObjectDataSource

• select methods must return a DataSet, Typed
  DataSet, IEnumerable implementation, Collection,
  or Array.
• Public Function GetCustomers() As DataSet
• Public Function GetCustomers() As
  CustomerDataSet
• Public Function GetCustomers() As
  CustomerCollection

14
Business Logic LayerRules for ObjectDataSource

• Insert, update, delete methods must take each
  field as individual parameters, or a single
  object containing fields as properties
• Public Sub Update(ByVal CustomerId As String, _
• ByVal CompanyName As String, _ByVal Address As
  String, ByVal City As String)
• Public Sub Update(ByVal oCustomersBLL As
  CustomersBLL)

15
Business Logic Layer

• Good NewsThe TableAdapter conforms to the
  requirements of the ObjectDataSource control!
• This means we can extend the TableAdapter control
  to add our own customizations such as validation

16
Business Logic Layer

• DEMO Creating the Business Logic Layer Component

17
Presentation LayerWeb UI

• User interface
• Input and validation
• ObjectDataSource can be used to bind UI Elements
  to Business Logic Layer components

18
Presentation LayerWeb UI

• DEMO Creating an input page using the GridView,
  ObjectDataSource, and BLL Component

19
Adding ValidationWeb UI

• GridView class exposes a RowUpdated event which
  is fired whenever a row is updated
• Protected Sub GridView1_RowUpdated(ByVal sender
  As Object, ByVal e As System.Web.UI.WebControls.Gr
  idViewUpdatedEventArgs) Handles
  GridView1.RowUpdated

20
Adding ValidationWeb UI

• RowUpdated Event e.Exception argument will
  contain any errors raised from the update
• Protected Sub GridView1_RowUpdated(ByVal sender
  As Object, ByVal e As System.Web.UI.WebControls.Gr
  idViewUpdatedEventArgs) Handles
  GridView1.RowUpdated
• If Not e.Exception Is Nothing Then

21
Adding ValidationWeb UI

• We can create a Custom Exception Class to raise
  Validation errors through the ObjectDataSource
  components Update Event.
• CExceptionDetail will hold single error
• CValidationException inherits from
  ApplicationException and holds List of
  CExceptionDetail.

22
Adding ValidationWeb UI

• DEMO Adding Validation to the Web UI

23
Presentation LayerWinForms UI

• We can reuse Business Logic Layer in WinForms
  Client
• Why WinForms?
• Smart Client
• WinForms are statefull
• Better DataBinding support
• Easy Distribution
• Web Browsers Suck!!!

24
Presentation LayerWinForms UI

• DEMO Creating the Windows UI

25
Adding ValidationWinForms UI

• DEMO Adding Validation to WinForms

26
A Quick word about Transactions

• For Web UIs, look at Transaction Attribute on
  Page
• For WinForms UIs, look at new System.Transactions
  .TransactionScope
• Ideally, should Introduce Business Façade Layer
  for Winforms